The present invention provides methods, apparatus and systems for reusing an application object for use with an application program, in which the object can be reused without causing nonconformity in the consistency or security, even if the object to be reused is updated. An example of a method includes detecting that the application program ends referring to the application object, detecting that the application object is updated by the application program, deciding to reuse the application object in response to detecting no update of the application object, making the application object reusable in response to the end of referring to the object, and decision to reuse the application object.